package org.review.datastructure;

import java.util.Arrays;
import java.util.Scanner;

public class ArrayStack {

    public static void main(String[] args) {
        //测试一下 ArrayStack 是否正确
//先创建一个 ArrayStack 对象->表示栈
        ArrayStack stack = new ArrayStack(4);
        String key = "";
        boolean loop = true; //控制是否退出菜单
        Scanner scanner = new Scanner(System.in);
        while (loop) {
            System.out.println("show: 表示显示栈");
            System.out.println("exit: 退出程序");
            System.out.println("push: 表示添加数据到栈(入栈)");
            System.out.println("pop: 表示从栈取出数据(出栈)");
            System.out.println("请输入你的选择");
            key = scanner.next();
            switch (key) {
                case "show":
                    stack.list();
                    break;
                case "push":
                    System.out.println("请输入一个数");
                    int value = scanner.nextInt();
                    stack.push(value);
                    break;
                case "pop":
                    try {
                        int res = stack.pop();
                        System.out.printf("出栈的数据是 %d\n", res);
                    } catch (Exception e) {
// TODO: handle exception
                        System.out.println(e.getMessage());
                    }
                    break;
                case "exit":
                    scanner.close();
                    loop = false;
                    break;
                default:
                    break;
            }
        }
        System.out.println("程序退出~~~");
    }

    int top = 0;//TODO top=-1 比较好理解，但是理解了原理都一样
    int maxSize;
    int[] stack;

    public ArrayStack(int maxSize) {
        this.maxSize = maxSize;
        stack = new int[maxSize];
    }

    public void push(int value) {
        if (isFull()) {
            System.out.println("栈已满");
            return;
        }
        stack[top++] = value;//TODO 这里初始top=-1，就是++top，先压栈再加 指向当前栈顶元素
    }

    public int pop() {
        if (isEmpty()) {
            System.out.println("栈已空");
            return 0;
        }
        return stack[--top];  //TODO 如果初始top=-1，就是top-- 先弹栈再减 指向一下个
    }

    public void list() {
        for (int i = top - 1; i >= 0; i--) {
            System.out.println(stack[i]);
        }
    }

    public boolean isFull() {
        return top == maxSize;
    }

    public boolean isEmpty() {
        return top == 0;
    }
}
